In JP 2004-162706A (Reference 1), as a valve timing controller having the above-described configuration, a technology in which a valve timing controller (variable valve timing device in Reference 1) is provided on an intake side cam shaft, and an actual valve timing is calculated based on a detection signal of a cam angle sensor that outputs a cam angle signal of the intake side cam shaft and a crank angle sensor that outputs a crank angle signal to a crankshaft, is described.
In Reference 1, a phase variable mechanism is configured to include an inner gear provided on the intake side cam shaft, an outer gear provided with the same axis as the inner gear, a planetary gear that meshes with the inner gear and the outer gear, and a motor for changing a revolving speed of the planetary gear. The phase variable mechanism can maintain the valve timing by matching a rotational speed of the motor with a rotational speed of the intake side cam shaft, and can set the valve timing to any of an advancing angle side and a retarding angle side by making the rotational speed of the motor faster or slower than the rotational speed of the intake side cam shaft.
Furthermore, in Reference 1, an amount of change in valve timing is calculated from a difference in rotational speed between the motor and the intake side cam shaft, and the final actual valve timing is calculated based on an amount of change between the actual valve timing and the valve timing.
In addition, as a valve timing controller having the above-described configuration, in JP 2017-8729A (Reference 2), a technology in which a valve timing controller (a variable valve timing mechanism in Reference 2) provided on an intake side cam shaft includes: a crank angle sensor that outputs a crank angle signal and a cam sensor that outputs a cam signal pulse corresponding to rotation of the intake cam shaft, and an actual rotation phase of the intake cam shaft is calculated based on a cam signal pulse detected first and a first reference position of the crank signal detected thereafter, after starting the cranking, is described.
In Reference 2, the cam sensor is configured to include a signal plate that rotates integrally with the intake cam shaft, and a rotation detection device that detects a plurality of protruding portions formed at an outer periphery of the signal plate. In this configuration, the entire periphery (region of 360 degrees) of the signal plate is equally divided into a plurality of regions, and different numbers of protruding portions are formed in parallel in a peripheral direction for each of the divided regions. In addition, one of the protruding portions is disposed at a boundary position of the divided regions. Therefore, when the intake cam shaft rotates, the rotation phase of the intake cam shaft is acquired by calculation based on the cam signal pulse when the rotation detection device first detects the protruding portion.
For example, considering the control when starting an internal combustion engine including the valve timing controller in the intake cam shaft, the cranking is started by the starter motor, the fuel is supplied to a combustion chamber after the rotational speed of the crankshaft rises to a value that enables the internal combustion engine to start, and an air-fuel mixture is ignited, but at the time of ignition, the opening and closing timing (valve timing) of the intake valve is set to a value appropriate for starting the starter motor.
In this manner, when the internal combustion engine is started, in order to set the opening and closing timing of the intake valve to a value appropriate for starting the internal combustion engine, it is necessary to acquire the actual opening and closing timing (actual valve timing) of the intake valve early.
However, since the final actual valve timing calculated by the processing described in Reference 1 can acquire the actual opening and closing timing (actual valve timing) of the intake valve in a situation where the internal combustion engine operates, the technology is inappropriate to acquire the opening and closing timing of the intake valve when starting the internal combustion engine.
Further, the technology described in Reference 2 can acquire the opening and closing timing of the valve when the internal combustion engine is started, but since the opening and closing timing of the valve is determined by acquiring the reference position of the crank angle signal after acquiring the first cam signal pulse, it takes time until acquiring the reference position from the crank angle signal after acquiring the cam signal pulse, and there is room for improvement.
Thus, a need exists for a valve timing controller which is not susceptible to the drawback mentioned above.